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Changing fork oil

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Changing fork oil

Post by Guest on Tue 16 Feb 2016, 4:27 pm

The forks on my CB have drain screws if that helps. I think my forks don't really dampen any more, they reach the end way too easy. I've read here that an oil change may do a lot of good. So I want to try that. How to do it easy (hopefully without need to take them out), is it just a matter of opening the top and drain, flush and refill? Also what oil? I suppose Haynes will tell me how much. Thanks.
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wornsprokets
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Re: Changing fork oil

Post by wornsprokets on Tue 16 Feb 2016, 5:44 pm

It forks out u wont get all oil out even with drain screws. With the centre stand down and a car jack under the engine would be the cheapest way. Loosen fork  top caps before u  take the forks and bolts loosened off, take each fork out take apart one at a time.  Drain oil out check see if fork springs are still ok by measurement, replace if needed.
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HomeBrew
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Re: Changing fork oil

Post by HomeBrew on Tue 16 Feb 2016, 8:27 pm

Yes remove the forks completely, make a note of how much sticks out at the top as it is very sensitive and critical to handling. 

Make sure to loosen the fork caps while they're still clamped in the bike because they are very tight and you cannot grip the tube. 

Remove the cap, spacer and spring, drain the oil into a measuring jug. Turn the fork upside down and pump the tube in and out to get all the oil. Personally I then rinse the tube out with petrol if its really dirty. Then whatever oil you took out put back in with new 10 wt, or you can measure from the top of the tube with it depressed, the spec is in haynes I think. 

Reassemble and you are good to go!
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jchesshyre
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Re: Changing fork oil

Post by jchesshyre on Tue 16 Feb 2016, 10:31 pm

I highly advise looking at Haynes for this. All the info you need is there and it's not a job I'd want to do for the first time without some kind of instruction and specification.
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eternally_troubled
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Re: Changing fork oil

Post by eternally_troubled on Wed 17 Feb 2016, 1:08 pm

While they (above) are correct in saying that you won't get 'all' of the fork oil out if you use the drain bolt you will get the vast majority of it out.

We're just all bitter because it was only one year of CB500 production that had fork-oil drain bolts - we all have to turn I bikes upside down to drain the oil out Wink

So, if you want to make sure you get every little bit of old oil out then I suggest that you remove the forks, drain and refill. If you don't care about every last little bit then just use the drain bolts...

The volume of fork oil to use is in the Haynes manual - it is different for different model years. If you can get a large plastic syringe it can be useful in measuring the oil.

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Re: Changing fork oil

Post by Guest on Wed 17 Feb 2016, 5:15 pm

Ohhh... nifty little drain bolts then hey. Great! Thanks for the advice, I'll follow you suggestions and will update this post when progressing. TA

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Re: Changing fork oil

Post by Guest on Fri 04 Mar 2016, 2:54 pm

Taking the top bolts off was not as 'tense' as I thought it would be, in fact it wasn't too hard to refit them by hand while maintaining a gentle force pushing down. Just used the drain bolts to pump the old oil out and rinsed with fresh spare fork oil. Forks stayed in place all the time with bike on centre stand. I may not have gotten all of it but at least most of it. This is what came out, and it stank. (20 years + ?)


And this is what went in, 'virgin picked honeydew' Smile 


Remember to put everything back in its proper place and sequence. Springs measured 307mm. Front suspension feels more solid and sturdy. Still need to do a road test. Thanks for the tips.
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jchesshyre
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Re: Changing fork oil

Post by jchesshyre on Fri 04 Mar 2016, 3:24 pm

I expect you'll be *delighted* when you road test it. I feel a really good improvement even changing the oil after 8-10,000 miles.
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eternally_troubled
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Re: Changing fork oil

Post by eternally_troubled on Sun 06 Mar 2016, 9:17 pm

That looks like the horrible stinking stuff that normally comes out, so it will probably be better when you ride it.

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Re: Changing fork oil

Post by Guest on Mon 14 Mar 2016, 2:07 pm

Ride is so much better with new shoes and fork oil change. Feels more sturdy, fork travvel is less now that the damping works properly. Also cornering with these new tires is smooth. Before the squared of rear had a sharp edge that felt like a sudden 'slipping'. Now all's fine. Recommend fork oil change.

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